Conductive mold rack for electrocleaning mold parts



Jan. 10, 1967 T. J. FARROW 3,297,559

CONDUCTIVE MOLD RACK FOR ELECTROCLEANING MOLD PARTS Filed June 21, 1963 4 sheets-sheet 1 INVENTOR. 70M /2 e a w Jan. 10, 1967 T. J. FARROW 3,297,559

CONDUCTIVE MOLD RACK FOR ELECTROGLEANING MOLD PARTS Filed June 21, 1963 4 Sheets-Sheet 2 I N VEN TOR. 75M [5 220 A) Q y gww MAM T. J. FARROW Jan. 10, 1967 CONDUCTIVE MOLD RACK FOR ELECTROCLEANING MOLD PARTS Filed June 21, 1963 4 Sheets-Sheet 5 INVENTOR 7/- ffzaezo w M fl/W firraZA/Fy-f T. J. FARROW Jan. 10, 1967 I CONDUCTIVE MOLD RACK FOR ELECTROCLEANING MOLD PARTS 4 Sheets-Sheet 4 Filed June 21, 1963 INVENTOR.

J/aeop/ BY M 9L 1477'0ZA/EVI United States Patent 3,297,559 CONDUCTIVE MOLD RACK FOR ELECTRO- CLEANING MOLD PARTS Tom Jay Farrow, Toledo, Ohio, assignor to Owens- Illinois Inc, a corporation of ()hio Filed June 21, 1963, Ser. No. 289,479 6 Claims. (Cl. 204242) This invention relates to a supporting rack for mold equipment, such as neck rings, molds, thimbles, bottom plates, etc., which are being cleaned.

More particularly, this invention relates to a supporting rack for supporting a plurality of neck rings, molds or thim bles, which operates as a simulated, conforming electrode that provides means for applying a D.C. current to the mold equipment and a surrounding frame of opposite polarity.

The rack of the invention may be used in the process set forth in my application Serial No. 288,329, filed June 17, 1963, now Patent No. 3,268,429.

Heretofore, the majority of mold cleaning work has been accomplished by a mechanical abrasion of the molding surfaces in a completely manual operation. The term manual is intended to indicate that each piece is handled and cleaned separately and independently of any other piece. As would be expected, manual cleaning of mold equipment is relatively time consuming and requires the constant attention of the operator who performs the cleaning. Also, this manual cleaning requires an operator with considerable skill so as to salvage as many molds as possible before they must be scrapped.

However, in the electrochemical cleaning process, as disclosed in my co-pending application above-referred to, a plurality of parts may be cleaned simultaneously by a single operator. No mechanical abrasion is necessary to complete the cleaning. This electrochemical cleaning operation involves several steps which, from the standpoint of the present application, requires the use of a rack or tray which may be alternately immersed in a series of tanks containing cleaning solutions and rinses. In particular, there must be two tanks which contain electrolytic caustic and in which provision must be made to connect DC. current to the mold parts cathodically when immersed in these tanks. The second tank requires that DC. current be applied to the mold parts and provision is made for periodically reversing the direction of flow of current to the mold parts so as to ultimately connect the parts being cleaned, cathodically and anodically.

The present invention directs itself to arack or tray on which mold equipment to be cleaned is placed after initial heating. The tray or rack serves to support the mold parts during their immersion in the plurality of tanks and also provides a relatively simple and expeditious means for electrically connecting DC. current to the mold parts and provides relatively equidistant current flow from the mold parts through the electrolytic caustic to the conforming opposite polarity electrode forming part of the rack. This generally, conforming electrode is incorporated as part of the rack structure and will be described in detail hereinafter in connection with the detailed description of the invention.

For electrochemical cleaning to be most effective, it is desirable that the current be connected to the mold part directly and that the current path from the mold part to the opposite polarity electrode be substantially equidistant with respect to the mold parts.

The rack should be an adequate conductor of electricity, make good electrical connection with power input and mold parts, not chemically react with the cleaning solution, be convenient to load and unload manually, and act as an efiicient supporting member which will not ice hamper the chemical, electrochemical or rinse operations involved in the process of cleaning molds.

With the foregoing in mind, it is an object of this invention to provide a tray or rack for supporting a plurality of mold pieces for simultaneous cleaning.

It is a further object of this invention to provide a mold supporting rack which provides electrical connection directly to the mold part to be cleaned.

It is an additional object of this invention to provide a supporting rack for mold parts to be cleaned which forms a generally conforming electrode with respect to the part to be cleaned.

Other and further objects will be apparent from the following description taken in conjunction with the annexed sheets of drawings, wherein:

FIG. 1 is a perspective view of the rack or tray of the invention with the tank, with which it is to be associated, shown in dotted lines;

FIG. 2 is a vertical cross-sectional view taken through the rack and tank of FIG. 1;

- FIG. 3 is an enlarged perspective view, partly in section, illustrating two modifications of the upper, conforming electrode;

FIG. 4 is a schematic side elevational view illustrating the cleaning operation of a neck ring supported by the rack and with current supplied thereto.

As pointed out previously, when electrochemically cleaning a piece of mold equipment, the most efiicient and effective manner of cleaning involves feeding the current directly to the mold part and providing equal current paths from the mold part to a conforming electrode. As a practical matter, to provide absolutely accurate conforming electrodes would be extremely expensive and would require that every piece of mold equipment, which are normally of various sizes and shapes in any one plant, have its own conforming electrode. Obviously, this would require keeping on hand electrode equipment of special design for each piece of mold equipment.

With this in view, applicant has invented a rack or tray which, as a practical matter, serves as a conforming electrode and is adjustable to a certain degree to accommodate itself to mold pieces of various sizes.

While the invention is described as being of particular use when electrochemically clean-ing glass forming mold equipment, it should be kept in mind that the principle of the invention is equally applicable to the cleaning of other metallic parts.

Referring specifically to FIGS. 1 and 2, the apparatus comprises an overhead channel iron 11} which has a block of insulating material 11 fixed to its underside at its lefthand end. A block 12 of conducting material is fixed to the underside of the insulating block 11 and has an inverted, V-shaped cut therein extending parallel to the length of the channel iron 10.

A block 13, similar to block 12, is fixed to the undersurface of the channel iron 10 at the right-hand end thereof. A copper bar 14 is fixed to the block 13 and extends along the inside of the channel 10 for a substantial distance thereof. v

A pair of vertically extending channel irons 15 and 16 are fixed to the undersurface of the channel iron 10 and serve to support a rectangular frame 17 formed of angle iron a predetermined distance below the channel iron 10.

Straps or bars 18 of copper are fixed to and extend the full length of the channel members 15 and 16. The rectangular frame 17 also carries copper strips 19 on the vertical outer surfaces thereof.

The rectangular frame 17 supports metal screening 20, thus forming a bottom for the tray which serves as a part of the aforementioned conforming electrode and through which cleaning solution or water may circulate.

A plurality of vertically extending walls 21 are fixed to the frame 17 and have a height nearly as high as the parts which are to be cleaned. The walls 21 form the sides of what, in effect, is an enclosure that surrounds the pieces to be cleaned.

A pair of vertically disposed rails or bars 22 and 23 extend the width of the tray and are spaced apart a small distance with the upper edges of the bars 22 and 23 adapted to support a plurality of neck ring halves, mold halves, etc., with the open sides of the neck rings being at the top. The rails or bars 22 and 23 are mounted to the frame 17 at their ends by C-shaped brackets 24a carrying insulating blocks 24 so as to effectively isolate the bars 22 and 23 from the rest of the apparatus. In the particular embodiment shown in the drawing, there are five pairs of rails or bars 22 and 23, it being understood that the specific device is designed to support a plurality of neck ring halves positioned side by side on each pair of bars or rails.

The vertical walls 21 are positioned between pairs of rails and serve as electrodes which will carry an opposite charge from that which is to be fed to the rails or bars 22 and 23.

A generally flat, overlying electrode, generally designated 25, is adapted to be supported for vertical movement relative to the main frame 17 and is formed of a rectangular piece of screening or expanded metal 26 supported about its periphery by a flat bar 27 with cross bars 28 and 29 fixed thereto to effectively support the expanded metal screen 26 in suspended position at a preselected distance above the articles or neck rings which are to be cleaned.

A pair of rods 30 and 31 are connected to the cross bars 29 of the overlying electrode 25. The rods 30 and 31 extend through openings formed in the channel iron and the copper bar 14. The rods 30 and 31 make good electrical contact with the copper 'bar 14 through the blocks 32 and 33. The rods 30 and 31 are adjustably connected to a pair of conducting blocks 32 and 33 adjacent their upper ends by thumb screws (see FIG. 1).

A convenient handle or lifting means 34 is connected to the upper ends of the rods 30 and 31. A lifting bracket 35 is also connected to the channel iron 10, intermediate its length, by which the rack of the invention may be raised and lowered. As previously stated, the block 13 at the right end of the channel iron 10 is electrically connected to the bar 14 which in turn is electrically connected to the frame 17, the vertical plates or walls 21, the overlying electrode 25 and the bottom 20. The block 12, at the left end of the channel iron 10, has a conducting strap or bar 36 connected thereto which is Z-shaped, with one leg of the Z extending parallel to the channel iron 10 but displaced-therefrom a distance approximately equal to one-half of the width of the rack 17. This bar or strap 36 carries a plurality of downwardly extending conducting members 37 equal in number to the pairs of rails 22 and 23. Each of the members 37 has a horizontal portion 38 fixed to its lower end, with each of the portions 38 being connected to the respective ends of copper conductive bars 39 which in turn are fastened to the side of rails 22. It should be pointed out that the rails 22 and 23 are connected together at their ends by member 40.

The rails 22 and 23, as previously stated, are isolated from the rest of the supporting rack by the insulating blocks 24. It should be pointed out that all the copper parts of the rack, with the exception of the parts thereof which will not be immersed, are covered by insulating material which is caustic and acid resistant. An example of such material is Unichrome S2l8-X of the Metal and Thermit Corporation. The rails or bars 22 and 23 are likewise coated.

The upper edges of the rails or bars 22 and 23 have the insulating material removed therefrom so that when a mold part or neck ring is resting on the rails 22 and 23, a good conducting path is provided for the DC. current to the mold part.

All of the other parts of the rack will be of an opposite polarity from the polarity of the rails or bars 22 and 23 and the mold parts supported thereby.

As can be seen when viewing FIGS. 1 and 2, the mold parts herein shown as neck rings N are mounted in the apparatus of the invention so that their open cavity portions face upwardly and the backs of the neck rings are supported on the rails 22 and 23. In this manner each row of neck rings is supported within an enclosure formed by the walls 21, the bottom 20 and the overlying member 26. The distances from the neck ring to the surrounding members is generally equal in all directions so as to effectively enclose each neck ring in a conforming electrode which will be of an opposite polarity to that of the neck itself.

As previously stated, the apparatus of the invention lends itself to utilization as a convenient device for sup porting mold parts or equipment throughout a mold cleaning cycle. This cycle includes as a necessary step thereof the application of periodically reversed DC. current imposed on the mold parts during their immersion within a bath containing an electrolytic caustic solution; for example, a solution containing 1.5 pounds of sodium hydroxide per gallon of water.

In order to provide periodically reversed current to the mold parts, it is necessary that each part be connected to a source of DC. current with the surrounding generally conforming part of the support rack being connected to the opposite terminal of the DC. current supplied. This current supply may be of the order of 3,000 amperes, with the voltage, however, maintained relatively low; for example, at 3-8 volts. The DC. current requirements for the cleaning of the mold equipment should be in the order of 200-300 amperes per square foot of mold surface area.

It has been applicants experience that the current may be fed to the mold par-ts by providing the tank 41, within which the mold parts are to be immersed, with a pair of brackets 42 located at opposite ends of the side wall of the tank at the upper edge thereof. These brackets are fastened to the tank with the upper edge extending outwardly therefrom and have an insulating block 43 fixed to the upper surface thereof. On top of each insulating block is provided a V-block 44 of highly conductive material. The V-blocks in turn have bus bars 45 fixed thereto. In this manner merely placing the rack within the tank 41 with the blocks 12 and 13 resting on the V-blocks 44, good electrical connection is made. Due to the fact that the current connected to the blocks 44 is of relatively low voltage, there is no danger to the operator when lowering the rack into the tank and positioning the blocks 12 and 13 onto the blocks 44. Furthermore, D.C. current may be continuously connected to the blocks 44, thus not requiring that the power may be turned on and off during the interval when the rack is not in position. Thus it can be seen that, upon immersing the rack in the tank 41 with the blocks 12 and 13 resting on blocks 44, DC. current will be fed through the conductive strips 14, 18, 19, 30 and 31 and also to the wire members 20 and 26 while at the same time current supplied to the block 12 will be connected 'by the bars 36 and 37 to the rails 22 and 23 on which the :mold parts are resting. This, in effect, provides current directly to the mold parts with the current path then being through the electrolyte to the oppositely charged generally conforming electrode formed by the rack.

Upon application of periodically reversed current to the two blocks 44, the polarity of the mold part and the generally conforming electrode will be reversed, thus setting up high turbulence at the mold faces due to the turnaround of the ions present adjacent the charged surface of the mold.

As would be expected, during the time when the mold parts are immersed in the tank, the electrolytic action will produce a considerable number of bubbles adjacent the mold surface. To insure proper electrolytic action, it is' necessary that these bubbles be permitted to escape from adjacent the mold surfaces and not be trapped thereabout.

For this reason, the upper electrode or member 25 is made of an open weave wire construction so as to permit bubbles to pass therethrough. Also, during the removal of therack from the tank it is important that excessive solution is not carried out with the rack, thus the wire screening and 26 prevent solution drag-out.

Referring to FIG. 3, there is disclosed two modifications which the upper electrode or overlying electrode 26 may take which provides current paths from the mold part to the electrode of even more precise equal distances.

As will readily be appreciated, the finish portion of the neck ring half N is concave, thus the center portion thereof will be a greater distance from the member 26 than the flat upper faces of the ring thereof. With this arrangement it would be expected that greater cleaning would occur on the faces rather than the concave portion of the finish and to overcome this deficiency, a rod or portion of a rod 46 may be fixed to the underside of the member 26 in position parallel to the axis of the neck ring half concavity.

A further modification is illustrated in FIG. 3 wherein a rod 47 is carried by a plate 48 which in turn is connected to the electrode 26. The conducting rod 47 and plate 48 are positioned so that the rod is co-axial with the concave finish or forming surface of the neck ring. In this manner the distance from the upper portion of the neck ring to the opposite polarity electrode and from the concave neck ring to the rod is the same and superior cleaning will therefore occur in the finish surface of the neck ring.

It should be pointed out that when other mold parts, having enlarged cavity halves, are placed within the rack of the invention, the vertical height of the upper electrode 26 may be adjusted and other configurations of more closely conforming electrode member, such as 46 and 47, may be supplied which follow the contour of the inner cavity of the mold pieces being cleaned.

Turning now to FIG. 4, there is shown in schematic form the electrical connection to a mold'part such as a neck ring N, and illustrates the manner of connecting the neck ring in the D.C. circuit.

It should be understood that like reference numerals are used in FIG. 4 for those parts which correspond to the parts illustrated in greater detail in the previous figures.

First considering the mold pieces to be cleaned as being connected anodically, the solid arrows illustrate the direction of flow of current from the conductor 12 through the conductor 37 to the rails 22 and 23 where the current enters the neck ring. The remaining parts of the rack are connected cathodically to the current supply. Current will flow in the direction of the arrows from the mold pieces to the generally conforming electrode formed by the walls 21, wire mesh bottom 20 and the upper electrode 26 with current flowing from the oppositely charged forming electrode members through conductors 30, 31 and 18 to the connection 13. With the mold part connected anodically, as illustrated in FIG. 4, a considerable amount of oxygen is liberated at the anode which in this case is the neck ring, and as illustrated the bubbles will rise and pass through the upper electrode 26, This formation of oxygen bubbles at the surf-ace of the mold will provide solution agitation at the mold surface to help remove loosened dirt from the surface of the part being cleaned.

As previously stated, when periodically reversed D.C. current is applied to the mold part, the part will be, for one period, acting as the anode and upon reversal of the current to the conductors 12 and 13 the mold part will be connected cathodically, at which time hydrogen will be liberated at the mold surface. With the mold surface positively charged, cleaning will be assisted by the fact that the positively charged metal parts repels positively charged particles of dirt. It has been found that carbon and some forms of iron oxide act a positively charged particles of dirt and will migrate away from the anode. Another advantage of having the part connected anodically for a short period of time is that the positively charged metal part will not attract metal ions which usually are in the form of a carbon smut. However, by utilizing a periodic reverse type system, the benefits of both direct current cleaning and reverse current cleaning is provided while at the same time a tremendous amount of turbulence occurs at the metal surface When the polarity is changed. It is believed that this turbulence or violent agitation is caused by the reversing of a polarized film that is immediately adjacent to the metal surface. When a mold piece is connected either anodically or cathodically, the solution in the immediate'vicinity of the metal part forms what is termed a polarized film. The parts which form the other electrode in the system have a polarized film which is just exactly opposite in polarity to the polarized film set up at the surface of the metal piece to be cleaned. When the current is reversed, this polarized film changes immediately to the opposite polarity which results in a turn of all the ions in the neighborhood of the electrodes. The rotation or displacement of these ions in the polarized film causes tunbulence adjacent the mold surface.

With the foregoing in view, it can be seen that applicant has provided a convenient apparatus for supporting mold pieces to be cleaned which lends itself to periodic reversed D.C. current 'being connected to the mold part being cleaned while the part is immersed in an electrolytic caustic bath.

Other and further modifications may be resorted to within the spirit and scope of the appended claims.

I claim:

1. Apparatus for electrochemical cleaning of mold parts comprising in combination, a generally rectangular tank adapted to contain an electrolytic caustic solution, a pair of electrical contacts carried by said tank at op 'posed sides thereof, said contacts being formed of inverted V blocks of conductive material insulated from the tank, a rack for supporting mold parts for immersion in said tank, said rack comprising a horizontal member of a length to span the distance between said contacts, said member carrying complementary contacts with inverted V-shaped bottom surfaces adapted to rest on said inverted V-shaped contacts carried by the tank, a pair of vertically extending, spaced apart members connected to said horizontal member, a rectangular frame having its opposite sides connected to the lower ends of said spaced apart members, a wire screen fixed to and spanning the width of said rectangular frame, a plurality of spaced vertical walls connected to said frame and extending the full width thereof, a plurality of pairs of rails insulatingly mounted on said frame with a pair of rails positioned in the space between each of said walls and extending parallel thereto, a flat, open weave, wire member of substantially the same size as the rectangular frame, means for adjustably mounting said wire member in spaced, overlying parallel relationship to said frame, conductive means connecting said rails together and to one of said complementary contacts whereby mold parts placed on said rails will be of one polarity and conductive means connecting the rest of the rack to said other complementary contact.

2. Apparatus for supporting metal parts to be cleaned in an electrochemical cleaning process comprising a horizontal conductive support member, a rectangular frame, conductive means connecting said frame in spaced, underlying relationship to said conductive member, a wire screen fixed to and spanning the area of said rectangular frame, a plurality of pairs of rails, insulatingly mounted on said frame, a fiat open weave wire member of substantially the same size as the rectangular frame, means for adjustably mounting said wire member beneath said horizontal conductive member, in overlying parallel relationship to said frame, means connecting said rails together as one polarity electrode whereby metal parts placed on said rails will be of one polarity and means connecting the rest of the apparatus as an oppositely charge generally conforming electrode.

3. Apparatus for supporting a plurality of metal parts to be cleaned in an electrochemical cleaning process comprising a rectangular frame, an open Weave, metallic screen fixed to and spanning the area of said rectangular frame, a plurality of spaced, vertically extending metallic walls connected to said frame, a plurality of pairs of rails insulatingly mounted on said frame with a pair of rails positioned in the spaces between said walls and extending parallel thereto, a fiat open weave wire member of substantially the same size as the rectangular frame, means for adjustably mounting said wire member in overlying parallel relationship to said frame, conductive means connecting said pairs of rails together as one polarity elec trode whereby metal parts placed on said rails will be of one polarity and conductive means connecting the rest of the apparatus as an oppositely charged generally conforming electrode.

4. Apparatus for supporting a plurality of mold parts to be cleaned in an electrochemical cleaning process comprising a rectangular frame, an open weave, metallic screen fixed to and spanning the area of said rectangular frame, a plurality of spaced apart, vertically extending metallic walls connected to said frame, a plurality of pairs of rails insulatingly mounted on said frame with a pair of rails positioned in the spaces between said walls and extending parallel thereto, a flat permeable member of substantially the same size as the rectangular frame, means for adjusta'bly mounting said member in overlying parallel relationship to said frame, first conductive means connecting said pairs of rails together as one polarity electrode whereby mold parts placed on said rails will be of one polarity, second conductive means connecting the rest of the apparatus as an oppositely charged generally conforming electrode, and means connecting said first and second conductive means to a source of DC. current of low voltage.

5. Apparatus for supporting metal parts to be cleaned in an electrochemical cleaning process comprising a horizontal conductive member, a pair of vertically extending, spaced apart members connected to said horizontal member, a rectangular frame having its opposite sides connected to the lower ends of said spaced apart members, a wire screen fixed to and spanning the width of said rectangular frame, a plurality of spaced vertical walls connected to said frame and extending the full width thereof, a plurality of pairs of rails insulatingly mounted on said frame with a pair of rails positioned in the space between each of said walls and extending parallel thereto, a flat, open weave, wire member of substantially the same size as the rectangular frame, means for adjustably mounting said wire member in paced, overlying, parallel relationship to said frame, conductive means connecting said rails together as an electrode having one polarity whereby metal parts placed on said rails will be of one polarity and means connecting the rest of the apparatus as an oppositely charged, generally conforming, electrode.

6. Apparatus for supporting metal parts to be cleaned in an electrochemical cleaning process comprising a horizontal conductive member, a pair of vertically extending, spaced apart members connected to said horizontal member, a rectangular frame having its opposite sides connected to the lower ends of said spaced apart members, a Wire screen fixed to and spanning the width of said rectangular frame, a plurality of spaced vertical walls connected to said frame, a plurality of pairs of rails insulatingly mounted on said frame with a pair of rails positioned in the spaces between said walls and extending parallel thereto, a fiat open weave wire member of substantially the same size as the rectangular frame, means for adjustably mounting said wire member to said horizontal conductive member in overlying parallel relationship to said frame, conductive means connecting said rails together as one polarity electrode whereby mold parts placed on said rails will be of one polarity and the rest of the rack comprises an oppositely charged, generally conforming, electrode.

References Cited by the Examiner UNITED STATES PATENTS 2,616,845 11/1952 Kreml 204242 2,760,929 8/1956 Shepard et al. 204-272 2,841,547 8/1958 Kotz et al 204-285 3,000,806 9/1961 Marotta et al. 204-285 3,023,154 2/1962 Hough et al. 204279 JOHN H. MACK, Primary Examiner.

W. VAN SISE, Assistant Examiner. 

1. APPARATUS FOR ELECTROCHEMICAL CLEANING OF MOLD PARTS COMPRISING IN COMBINATION, A GENERALLY RECTANGULAR TANK ADAPTED TO CONTAIN AN ELECTROLYTIC CAUSTIC SOLUTION, A PAIR OF ELECTRICAL CONTACTS CARRIED BY SAID TANK AT OPPOSED SIDES THEREOF, SAID CONTACTS BEING FORMED OF INVERTED "V" BLOCKS OF CONDUCTIVE MATERIAL INSULATED FROM THE TANK, A RACK FOR SUPPORTING MOLD PARTS FOR IMMERSION IN SAID TANK, SAID RACK COMPRISING A HORIZONTAL MEMBER OF A LENGTH TO SPAN THE DISTANCE BETWEEN SAID CONTACTS, SAID MEMBER CARRYING COMPLEMENTARY CONTACTS WITH INVERTED V-SHAPED BOTTOM SURFACES ADAPTED TO REST ON SAID INVERTED V-SHAPED CONTACTS CARRIED BY THE TANK, A PAIR OF VERTICALLY EXTENDING, SPACED APART MEMBERS CONNECTED TO SAID HORIZONTAL MEMBER, A RECTANGULAR FRAME HAVING ITS OPPOSITE SIDES CONNECTED TO THE LOWER ENDS OF SAID SPACED APART MEMBERS, A WIRE SCREEN FIXED TO AND SPANNING THE WIDTH OF SAID RECTANGULAR FRAME, A PLURALITY OF SPACED VERTICAL WALLS CONNECTED TO SAID FRAME AND EXTENDING THE FULL WIDTH THEREOF, A PLURALITY OF PAIRS OF RAILS INSULATINGLY MOUNTED ON SAID FRAME WITH A PAIR OF RAILS POSITIONED IN THE SPACE BETWEEN EACH OF SAID WALLS AND EXTENDING PARALLEL THERETO, A FLAT, OPEN WEAVE, WIRE MEMBER OF SUBSTANTIALLY THE SAME SIZE AS THE RECTANGULAR FRAME, MEANS FOR ADJUSTABLY MOUNTING SAID WIRE MEMBER IN SPACED, OVERLYING PARALLEL RELATIONSHIP TO SAID FRAME, CONDUCTIVE MEANS CONNECTING SAID RAILS TOGETHER AND TO ONE OF SAID COMPLEMENTARY CONTACTS WHEREBY MOLD PARTS PLACED ON SAID RAILS WILL BE OF ONE POLARITY AND CONDUCTIVE MEANS CONNECTING THE REST OF THE RACK OF SAID OTHER COMPLEMENTARY CONTACT. 